This ultrasound diagnostic device (1) is characterized by being provided with: an image acquisition unit (3) which generates an ultrasound image; an image recognition unit (9) which performs image recognition on an ultrasound image to calculate a recognition score; an index value calculation unit (10) which, on the basis of the recognition scores calculated for a determined number of ultrasound images, calculates an index value of multiple regions; a region narrowing unit (11) which, on the basis of the index value, narrows the multiple regions to target regions where region determination will be performed; and a region determination unit (12) which, on the basis of the recognition scores calculated by the image recognition unit (9), determines, for a target region narrowed by the region narrowing unit (11), an imaging region on a subject.